AB0717 DIAGNOSIS OF CRANIAL GIANT CELL ARTERITIS IN JAPAN USING VASCULAR ULTRASONOGRAPHY COMBINED WITH OTHER COMPLEMENTARY IMAGING METHODS
Authors: T. Kawamoto, M. Ogasawara, Y. Mastuki-Muramoto, M. Harada, E. Hayashi, M. Matsushita, K. Yamaji, N. Tamura
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> The utility of vascular ultrasonography (v-US) was proved recently in European countries, due to which the technology, diagnosis, and classification methods have been spreading. However, the use of v-US is not prevalent in Japan. Therefore, giant cell arteritis (GCA) is usually diagnosed by combining v-US with other imaging methods scrupulously. Furthermore, progressive Computed Tomography Angiography (CTA) technologies, increased use of Positron Emission Tomography (PET-CT), and a high population with Takayasu disease are found in Japan. <h3>Objectives</h3> Giant cell arteritis of cranial type (c-GCA) can quickly lead to blindness and stroke. Therefore, a rapid and appropriate diagnostic method is required to differentiate between c-GCA cases and those mimicking c-GCA. Thus, we aimed to construct a diagnostic method for c-GCA by optimizing the available imaging methods in Japan and using v-US as a diagnosing method from Europe. <h3>Methods</h3> We targeted 56 patients with suspected GCA, who visited our hospital from 2019 to 2022. v-US had been performed previously in all patients and 23 patients were diagnosed with GCA. These GCA patients were classified as c-GCA vs c-GCA + Large vessel (LV)-GCA vs LV-GCA in the ratio 11: 6: 6. In this study, we established 17 cases as c-GCA, and the other 39 as mimic cases using clinical and imaging methods. Furthermore, we analyzed and compared 31 patients evaluated with v-US from 2021 to 2022 using a vascular map, which was originally made by us and we were making maps for blood flow and writing down clinical symptoms evaluated at three stages. <h3>Results</h3> The sensitivity of the imaging methods to c-GCA patients was high for v-US (82.3%), Temporal artery biopsy (TAB) (78.6%), and CTA (71.4%) and low for PET-CT (50.0%) and Magnetic resonance imaging angiography (MRI/A) (38.5%). However, we did not use a contrast agent for MRI/A because our main objective to perform MRI/A was to distinguish cerebral infarction. The match rate of the imaging methods between v-US and PET-CT was 87.5% (CTA: 71.4%, TAB and v-US: 64.3%, and CTA: 63.6%). Among the 39 mimic cases, 15 cases were found to be Polymyalgia Rheumatica (PMR), 6 cases were LV-GCA, 5 cases were chronic headache, and others were collagen diseases, including 2 cases of Takayasu diseases. In 31 cases (10 cases of c-GCA and 21 mimic cases) from 2021 to 2022, halo sign of v-US (p-value: 0.01), jaw claudication (p-value: 0.02), and temporal headache on both sides (p-value: 0.01) were significant statistically. <h3>Conclusion</h3> In this study, we constructed a flowchart to diagnose c-GCA in Japan using v-US and other complementary imaging methods. First, we distinguished GCA cases from mimic cases with high precision. Thereafter, we combined imaging methods, which contributed highly to diagnosis in our results. Lastly, we considered the accommodation of TAB. We have started using this flowchart, and this contribute to be higher rate of diagnosing GCA and decreasing blindness and stroke. <h3>References</h3> [1]Ponte C, Grayson PC, Robson JC, et al.. 2022 American College of Rheumatology/EULAR classification criteria for giant cell arteritis. Ann. Rheum. Dis. 2022;81(12):1647–1653. [2]Ponte C, Martins-Martinho J, Luqmani RA. Diagnosis of giant cell arteritis. Rheumatol. (Oxf. Engl.). 2020;59(Suppl 3);Suppl 3:iii5–iii16. <h3>Acknowledgements:</h3> NIL. <h3>Disclosure of Interests</h3> None Declared.